Turbine bucket wheel notch block



TURBINE BUCKET WHEEL NOTCH BLOCK Filed Jan. 4, 1936 Inventor: Rudolph Hillner,

l-ii Attorngg.

Patented Dec. 28, 1937 TURBINE BUCKET WHEEL NOTCH BLOCK Rudolph Hillner, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York 7 Application .lanuary'4,,1936, Serial No. 57,593 '2 Claims. (crass-'17) inventionrelates-morespecifically to the kind of bucketwheels which comprise a disk element and a row or rows of buckets secured to the disk element by a dovetail connection between a base portion of each bucket and the rim of the wheel. w In the usual arrangement of this kind, shoulder portions of the dovetail-forming rim portion are cut away to define a notch opening through 'whichthe buckets are inserted and slid along the rim during assembly. Difficulties are experienced in closing these notch openings by means of a notch opening bucket or a notch opening block in order. to prevent relative movement of the buckets on the rim, and lock them in place and also in order to fill out the contour of the wheel. a In modern high speed turbines where the buckets are subjected to considerable, centrifugal forces,

it is sometimes undesirable to insert in the notch opening a bucket because of the great centrifugal forces and, in many cases, it is not even desirable 25 to put into the notch opening aheavy block or filler. V V a The object of the present invention is to provide animproved construction and arrangement of bucket wheels of the, type above referred to whereby the buckets are rigidly secured to the rim of the disk and prevented from relative movement thereon- For a'consideration of what I believe to be novel and my invention, attention is directed to the following description and claims appended thereto in connection with the accompanying drawing. I

In the drawing, Fig. 1 illustrates an exploded,

perspective view of a bucket wheel portion embodying my invention; Fig. 2 is an enlarged, sectional view through the notch opening of the bucket wheel shown in Fig. 1 and Fig. 3 is a perspective view of the assembled bucket wheel.

The arrangement comprises a disk or disk 45 member Illhaving a grooved rim portion defining a dovetail II. The dovetail of the rim forms shoulders l2 and I3 which are partly cut away to form a notch opening l4 (Fig. 1 Buckets l5 comprising blades l6. and base portions", which 50 latter define, inverted dovetails, are inserted through the notch opening and slid to the left .or right along the rim of the wheel. In order to prevent relative movement'between the row of buckets and the disk, a forked member or fork I8 is provided in the 'notch opening, which member has legs I9, straddling the rim and filling the cut-away shoulder portions thereof. This fork or filling member in accordance with my invention is securely attached to the rim and prevented fromradial movement due to the'action of centrifugal force exerted thereon by 7 means of two grub screws, bolts or like locking means 2|, 22. In order to distribute the forces exerted on the grub screws or bolts substantially along their entire length threaded bores 23, 24

are formed in the adjacent portions of the rim and the fork l8 for engaging the screws.

During manufacture and assembly the buckets with. their bases are slid along the rim of the disk. After all the buckets have thus been assembled on the disk, the fork I8 is inserted in the notch opening and thereafter the threaded bores 23, 24 are formed so that one half or side of the lower part of each boreis defined by the fork and the other half by the rim. Finally, the

grub screws which in substance represent radially inserted locking members are screwed into the threaded bores thus formed and locked in position by peening over portions (Fig. 2) on. the outer surface of the fork to engage the rounded heads of the screws. The outer ends of the bucket blades are held together in known manner by a shroud band 26 (Fig. 3).

- With my inventionI have accomplished a simple arrangement for closing notch openings of bucket wheels by means of a forked member and holding such member securely in position, thus preventing it from movement by high, centrifugal forces exerted thereon. The arrangement is'reliable in operation and may be manufactured at comparatively low cost. The forked element is held by the screws with sufficient strength to permit in certain cases the provision of said element with a bucket blade.

Having described the method of operation of apparatus shown is only illustrative and that the.

invention may be carried out by other means.

What I claim as new and desire to secureby Letters Patent of the United States, is:

1. A bucket wheel comprising a disk member having a rim and a row of buckets having bases forming a dovetail connection with the rim, a portion of the rim being cut away to form a notch opening through which the buckets are inserted during assembly, means for closing the notch opening to prevent relative movement between the disk member and the buckets, said means comprising an element having legs straddling the rim and disposed in the notch opening and grub screw means secured in threaded radial bores formed in adjacent portions of the rim and the legs, and means to prevent loosening of the grub screw means.

2. A bucket wheel comprising a disk member having a rim and a row of buckets having bases forming dovetail connections with the rim, a portion of the rim being cut away to form a notch opening through which the .buckets are inserted screws in position. I

RUDOLPH HILLNER. 

